The present invention pertains to a device for replacing toothed belt pulleys on motor vehicle engines, comprising a pull-off disk, which is provided with at least two tie rods, which can be brought into engagement with at least two openings of the toothed belt pulley in an axially firmly seated manner for pulling off the toothed belt pulley, and a spindle drive, which is arranged essentially centrally in the pull-off disk and by the actuation of which the toothed belt pulley is pulled off from its seating by means of the pull-off disk engaging the toothed belt pulley.
A device of this type (prospectus of the company Facom; xe2x80x9cFacom-Automativxe2x80x9d Sonderaktion 98-99, page 8) has been known, which comprises a pull-off disk, which is provided with three tie rods. This prior-art device is used to replace toothed belt pulleys of a motor vehicle engine, which are provided for driving, e.g., the camshaft of the motor vehicle engine. To pull off the toothed belt pulley, this prior-art device with its tie rods can be engaged with three corresponding openings of the toothed belt pulley in an axially firmly seated manner.
The tie rods have an essentially cylindrical design and have at their free end located toward the toothed belt pulley a receiving groove directed in the circumferential direction of the pull-off disk, with which groove they can be brought into positive-locking engagement with the edge areas of one of the openings of the toothed belt pulley.
Furthermore, the pull-off disk of the prior-art device is provided with an essentially centrally arranged spindle drive, by the actuation of which the toothed belt pulley is pulled off from its seating by means of the pull-off disk engaging the toothed belt pulley and the tie rods of the said pull-off disk. The spindle drive is actuated by means of a commercially available wrench, e.g., in the form of a so-called ratchet, which is placed on a corresponding drive hexagon of the spindle drive.
In the prior-art device, the spindle drive comprises a pressure screw, which has the above-mentioned drive hexagon on its outer free end and which is screwed axially adjustably into a central, threaded through hole of the pull-off disk. During the pull-off operation, this pressure screw presses with its end located opposite the drive hexagon the seating or the end of the camshaft on the front side, so that an axial relative movement of the pull-off disk in relation to the camshaft will be obtained. Since the pull-off disk with its tie rods in the openings of the toothed belt pulley engages the toothed belt pulley in an axially firmly seated manner, the toothed belt pulley is pulled off from its seating at the same time during this operation.
In the case of toothed belt pulleys seated extremely firmly on their seating, it is frequently necessary to lock the toothed belt pulley in its particular rotated position. A so-called drive belt lock, which comprises a toothed belt band and a locking lever, is provided for this purpose according to page 9 of the above-mentioned company catalog. To lock the toothed belt pulley, the toothed belt band is placed around the toothed belt pulley and is connected by its two ends to the locking lever. The fastening of the toothed belt band to the locking lever is selected to be such that a certain pretension of the toothed belt band is obtained during the locking and the toothed belt band surrounds the toothed belt pulley with its teeth in a firmly seated manner. This so-called drive belt lock may also be used to loosen the fastening screw connection of the toothed belt pulley before the toothed belt pulley is pulled off from its seating.
This means that two tools, which must be attached separately to the toothed belt pulley in order to remove the toothed belt pulley, are needed to lock the toothed belt pulley, on the one hand, and to pull off the toothed belt pulley from its seating, on the other hand. The handling especially of the drive belt lock is very complicated, so that slipping off of the drive belt lock, e.g., due to incorrect attachment to the toothed belt pulley, is easily possible. Furthermore, the drive belt lock must be attached to the toothed belt pulley twice, namely, once to loosen the fastening screw connection and again to attach the pull-off disk with its tie rods and to be able to actuate the spindle drive because the drive belt lock is not held automatically in a firmly seated manner at the toothed belt pulley. It is not possible to attach the pull-off disk before the fastening screw connection has been loosened because the fastening screw is not accessible from the outside with a corresponding wrench when the toothed belt pulley is attached.
To avoid the complicated attachment of the drive belt lock, at least to loosen the fastening screw connection, a lever tool, which is called a drive disk carrier and which can likewise be brought into engagement with corresponding openings with locking pins in a positive-locking manner, has been known from page 8 of the above-mentioned company catalog. The fastening screw connection of the toothed belt pulley is freely accessible from the outside in the case of this wrench and this drive disk carrier can also be inserted into the corresponding openings of the toothed belt pulley in a very simple manner. Thus, two individual tools, which must be engaged individually with the toothed belt pulley, are necessary to replace a toothed belt pulley according to the devices known from the said company catalog of the firm of Facom, and three individual tools are necessary for simple handling, because the drive disk carrier cannot be used for the use of the pull-off disk, either, because due to its shape, this drive disk carrier covers from the outside the openings of the toothed belt pulley which the tie rods of the pull-off disk must engage to pull off the toothed belt pulley, i.e., the drive belt lock must always be used to lock the toothed belt pulley when the pull-off disk is used.
Consequently, the primary object of the present invention is to improve a device of this type for removing or replacing toothed belt pulleys such that an extremely simple and safe handling is guaranteed, and, in particular, the above-mentioned drawbacks of the prior-art device are avoided.
This object is accomplished according to the present invention in that to receive the spindle drive, the pull-off disk has a central, threaded through hole, through which a wrench can be attached to the fastening screw connection of the toothed belt pulley, and that the pull-off disk has at least one additional opening for receiving in a positive-locking manner a coupling piece of a locking tool, by which the toothed belt pulley can be locked in its particular rotated position by means of the pull-off disk.
An extremely simple device which can be handled in a reliable manner is made available for replacing toothed belt pulleys due to an embodiment according to the present invention.
To receive the spindle drive, the pull-off disk is provided for this purpose with a central, threaded through hole, through which a wrench can be attached to the fastening screw connection of the toothed belt pulley. Such a wrench may be, e.g., a standard socket in conjunction with a ratchet. Provisions are made according to the present invention for the threaded through hole to have a correspondingly large diameter for the spindle drive, through which such a socket can be inserted to loosen the fastening screw connection of the toothed belt pulley and attached to the fastening screw connection.
At the same time, the pull-off disk is provided with at least one additional opening to receive a coupling piece of a locking tool in a positive-locking manner. Such a locking tool may be, e.g., a simple, bent locking lever, at the bent end piece of which a corresponding coupling piece is provided. This coupling piece may be designed, e.g., as a simple square, which can be introduced into the additional opening of the pull-off disk in a positive-locking manner.
The pull-off disk according to the present invention is thus hung with its tie rods into the openings of the pull-off disk in a simple manner and is brought into engagement with same in a positive-locking manner, e.g., in the manner already known from the state of the art described in the introduction.
The spindle drive is therefore removed from the threaded through hole of the pull-off disk to loosen the fastening screw connection. To loosen the fastening screw, the fitting wrench is correspondingly attached to the fastening screw and the toothed belt pulley is locked in the particular rotated position by means of the locking tool, so that the toothed belt pulley is also locked because of the positive-locking connection with the pull-off disk and with the tie rods of the pull-off disk. Simple loosening of the fastening screw connection can be carried out in this mounted position of both the wrench for the fastening screw connection and the locking tool and the pull-off disk with its tie rods.
After the fastening screw connection has been loosened, the wrench is removed together with the fastening screw connection and the spindle drive is inserted into the central threaded through hole of the pull-off disk.
By subsequently actuating the spindle drive, the spindle drive is supported, as is known from the prior art, on the front side on the corresponding shaft, to which the pull-off disk is attached, so that the toothed belt pulley is pulled off by means of the pull-off disk and the tie rods engaging the toothed belt pulley. The rotated position of the toothed belt pulley can be locked by means of the locking tool at the same time even in the fixed position of the toothed belt pulley, so that the correspondingly necessary strong pulling forces can also be applied via the pull-off disk and the tie rods even at a high drive torque on the spindle drive, without the toothed belt pulley, on the one hand, and the correspondingly locked camshaft, on the other hand, being able to rotate.
Thus, the embodiment according to the present invention provides a device with which a toothed belt pulley can be removed from its seating with the lowest possible effort and with extremely simple handling.
The seatings are usually coordinated with the dimensions of the toothed belt pulley such that it can be mounted in the reverse direction in a simple manner.
To do so, the fastening screw connection is again attached with the toothed belt pulley mounted and tightened by means of a wrench. The pull-off disk with its tie rods now again engages the openings of the toothed belt pulley and can be locked in the desired rotated position by the locking tool, which is received in the additional opening in a positive-locking manner. A corresponding tightening of the fastening screw connection can thus also be carried out reliably and correctly.
According to another aspect of the invention, the tie rods can be received in the pull-off disk in radially extending guide slots in a radially adjustable manner. Due to this adjustable mounting, the tie rods can be adapted to different toothed belt pulleys with openings arranged differently in a simple manner. The device according to the present invention with its pull-off disk according to the present invention can thus also be used for toothed belt pulleys of different shapes.
Due to the embodiment according to another aspect of the invention, the pull-off disk can be connected in a fixed manner to the toothed belt pulley by means of the tie rods. To do so, the tie rods are provided with a guide section each, with which they can be received in the corresponding guide slot of the pull-off disk in an axially displaceable and nonrotatable manner. The guide sections have at least two guide surfaces, which extend in parallel to the corresponding central longitudinal axis of the tie rods and by which the tie rods are guided in the correspondingly associated guide slot of the pull-off disk with a small clearance.
For the axial adjustment, provisions are made according to another aspect of the invention to provide the tie rods with corresponding adjusting nuts. The pull-off disk can be braced in a firmly seated manner against the toothed belt pulley by these adjusting nuts and the tie rods engaging the toothed belt pulley. This in turn means that the pull-off disk can be arranged on the toothed belt pulley in a firmly seated and simple manner and a further attachment of both the wrench for loosening of the fastening screw connection and of the locking tool to the pull-off disk can be performed in a simple manner, without the pull-off disk with its tie rods being able to become detached from the toothed belt pulley. In particular, the handling of the device according to the present invention is considerably facilitated as a result.
Due to the embodiment according to another aspect of the invention, the tie rods can be caused to engage edge areas of the openings of the toothed belt pulley, which edge areas are located to the left and right in the direction of rotation in the circumferential direction. Provisions are made for this purpose for the tie rods to be provided at their corresponding ends facing the toothed belt pulley with circular stop webs, with which the tie rods extend behind the corresponding openings of the toothed belt pulley in some areas in a positive-locking manner. Due to the circular shape of these stop webs, such a positive-locking engagement can be performed reliably in the edge areas of the openings located to the right and to the left in the circumferential direction, as was mentioned above. This is especially advantageous during the tightening of the fastening screw connection, because the tie rods can now be arranged in the corresponding edge area of the openings against the respective direction of rotation during the tightening of the fastening screw connection and are blockingly in contact with this edge area against the direction of rotation occurring during the tightening, so that slipping off from the openings is reliably prevented from occurring.
To secure a defined position of the pull-off disk during use, the pull-off disk according to another aspect of the invention has an at least partially circular centering shoulder, with which it can be inserted into the toothed belt pulley or attached to the toothed belt pulley in a centered manner.
To make it possible to attach the pull-off disk according to the present invention to toothed belt pulleys of different sizes in a centered manner, provisions are made according to another aspect of the invention for the pull-off disk to have a plurality of centering shoulders adapted in diameter to these sizes of the toothed belt pulleys.
According to another aspect of the invention, it is also possible to provide a plurality of guide slots in the pull-off disk, whose number and arrangement are adapted to the number and arrangement of the openings in the toothed belt pulley. Provisions are now made, in particular, for the number and the arrangement of the guide slots in the pull-off disk to be selected to be such that the pull-off disk can also be used for different toothed belt pulleys with openings arranged differently. For example, four guide slots may be arranged in a cross-shaped pattern in relation to one another, and two additional guide slots, which are arranged at an angle of 120xc2x0 to each other and in relation to one of the four guide slots, are additionally associated with these guide slots. As a consequence, toothed belt pulleys provided with two diametrically opposed openings, with four openings arranged in a cross-shaped pattern or with three openings arranged at 120xc2x0 in relation to one another can be replaced with such a pull-off disk. Corresponding to the number of openings present in the toothed belt pulley, at most only as many tie rods can be used as are brought into engagement with the corresponding openings. In a preferred embodiment, a plurality of groups of radial guide slots are provided, whose groupwise angular arrangement in the pull-off disk is selected to be such that the pull-off disk can be used for toothed belt pulleys with two, three, four, five, six or seven openings arranged distributed uniformly on the circumference. For example, only two diametrically opposed guide slots with tie rods inserted. correspondingly in these are used in this variant, e.g., in the case of the crosswise arrangement of four openings in the toothed belt pulley. If, in contrast, the toothed belt pulley has, e.g., six openings, only three guide slots with an angular offset of 120xc2x0 in relation to one another may be sufficient with corresponding tie rods.
Since the pull-off disk has only a limited area for arranging the radial guide slots, pull-off disks of different designs with different arrangements of guide slots may also be provided for pulling off toothed belt pulleys of different shapes according to another aspect of the invention.
To obtain the simplest and least expensive spindle drive possible, provisions are made according to another aspect of the invention for the spindle drive to have a threaded sleeve, which can be screwed into the threaded hole of the pull-off disk and which is in turn provided with a corresponding threaded hole to insert a pressure screw. The pressure screw may have a known design as is known from the state of the art and is correspondingly used during its actuation to pull off the toothed belt pulley. Due to the provision of this separate threaded sleeve, the central threaded through hole in the pull-off disk can have a sufficiently large dimension in order to pass through the wrench to be attached to the fastening screw connection. On the other hand, however, the diameter of the pressure screw may also be selected to be smaller, because a diameter compensation is achieved by means of the threaded sleeve provided.
According to another aspect of the invention, a pressure piece may be provided, which can be inserted with a centering pin into a threaded hole of the fastening screw connection of a toothed belt shaft to support the spindle drive during the pulling off of the toothed belt pulley in a centered manner. It is known that toothed belt pulleys are screwed to the camshaft and to their seating in a firmly seated manner by means of nuts and a corresponding threaded pin of the camshaft. Furthermore, designs have also been known in which the camshaft has a threaded hole, into which a corresponding fastening screw is inserted, instead of these fastening nuts with threaded pin. Since the screw-in thread for the fastening screw is still present in the center of the camshaft after the loosening of this fastening screw connection in the form of a fastening screw, the pressure piece with its centering pin is provided, with which the pressure piece can be inserted into the threaded hole with a clearance. The pressure piece is now supported with a circular contact web, which is larger than the centering pin, on the circular front ring located around the screw-in thread, so that damage during pulling off, especially in the case of strong pressing forces of the spindle drive on the mounting thread of the camshaft, is ruled out with certainty. To make it possible to insert the pressure piece into the threaded hole of, e.g., the camshaft as simply as possible, the centering pin may also have a conical shape.
To obtain a sufficiently great path of adjustment of the device, the pull-off disk may have, according to another aspect of the invention, an outwardly directed threaded dome in the area of its central threaded through hole to receive the spindle drive. It is possible due to this embodiment to increase the axial distance between the spindle drive and the toothed belt pulley such that, e.g., an axially projecting mounting hub of the toothed belt pulley can also be received in the central threaded through hole of the pull-off disk or that this threaded hole can be radially expanded in this area located axially toward the toothed belt pulley, so that this mounting hub is securely held in the pull-off disk during the pull-off operation or with the pull-off disk attached.
According to another aspect of the invention, the pull-off disk may also have a bell-shaped design for a similar purpose and have a circular support wall, with which the pull-off disk can be attached to the toothed belt pulley in a centered manner. It is also ensured by this design that the pull-off disk cannot collide with an axially projecting mounting hub of the toothed belt pulley during the attachment of the pull-off disk.
To further simplify the design of the pull-off disk, provisions may be made according to another aspect of the invention for the additional opening to be formed by one of the guide slots, which is provided to receive a tie rod. Provisions are also made for the dimensions of the guide slots to be selected to be such that these can be used alternatingly to receive the guide section of a tie rod or the coupling section of the locking tool.
Due to the embodiment according to the present invention according to another aspect of the invention, contact of the mounting section with one of its contact surfaces in the corresponding opening of the toothed belt pulley over the largest possible area is obtained during use. This in turn causes a considerable reduction in the contact pressure between the contact surface and the corresponding opening of the toothed belt pulley, so that damage especially to the toothed belt pulley is prevented from occurring with certainty. The tie rods have a mounting section for this purpose with at least one contact surface bent radially in the outwardly direction, whose radius of curvature approximately corresponds to the radius of an opening of the toothed belt pulley, which opening is engaged by the tie rod for pulling off the toothed belt pulley.
As was mentioned above in connection with another aspect of the invention, the number of guide slots is adapted to the number and arrangement of the openings in a toothed belt pulley. Due to the many different possible applications for different toothed belt pulleys, it is always guaranteed that at least one of the guide slots provided will not be used.
Thus, if, e.g., only two openings are provided in the toothed belt pulley, but more than two guide slots are provided in the pull-off disk, one of the additional guide slots can be used to receive the locking tool.
The device according to the present invention thus makes available a device for replacing toothed belt pulleys of a motor vehicle engine which can be handled in an extremely simple manner, on the one hand, and with which both the loosening of the fastening screw connection and the pulling off of the toothed belt pulley with the fastening screw connection removed can be performed, on the other hand, in a simple manner. It is guaranteed that the toothed belt pulley can also be securely locked in its rotated position.
The various features of novelty which characterize the invention are pointed out with particularity in the another aspect of the inventions annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.